The present invention relates to a method of correcting dynamic unbalance of a tire.
In general, a pneumatic tire has dynamic unbalance more or less. If a tire having a heavier part is rotatably supported with its rotational axis kept horizontally, the heavier part probably comes down. Such a tire can be said as being in a statically unbalanced state. Although a tire is statically balanced, a precessional motion is sometimes observed when the tire is rotated at a high speed. Such a tire can be said as being in a couple-unbalanced state. The dynamic unbalance includes such static unbalance and couple unbalance.
Conventionally, dynamic unbalance of a wheel, here which means an assembly of a tire and a wheel rim, is corrected by fixing a counter weight made of lead or brass to the flange of the wheel rim. Thus, the tire itself is not improved in the dynamic unbalance. Accordingly, if the tire is remounted or the wheel rim is replaced with another, the wheel must be balanced again.
In the laid-open japanese patent application JP-A-7-113715, a counter weight fixed to the inner surface of a tire is disclosed, wherein the counter weight is a heavy paste containing metal powder having a high specific gravity. Thus, during high speed running, a centrifugal force of the counter weight concentrates on a narrow region of the tire inner surface to lift up this region, and the tread portion is partially deformed to increase the radial force variation.
An object of the present invention is to provide a method of correcting dynamic unbalance of a pneumatic tire it self, by which the radial force variation is not increased.